The invention relates to the technical sector of methods for transferring articles between two automatic machines arranged in line.
The simplest method is performed using a transport line which collects the articles exiting from the first machine in order to transfer them to the second machine.
This method is rather “rigid” in the sense that it is able to perform the relative tasks only under regular functioning conditions of both the upstream and the downstream machines.
In many applications there is the need to make this transfer more flexible, such that it can overcome temporary malfunctioning or short unforeseen halts in a machine without having repercussions on the other machine.
There exist various types of machines which, because of their intrinsic characteristics, incur negative effects from even a brief halt caused by malfunctioning of another machine, functionally associated thereto.
In order to obtain the desired characteristics of flexibility, transfer methods occasionally employ temporary stores, also known as buffers, suitable for the specific purposes of at least one or possibly both of the machines involved.
In some cases, in which the more “delicate” machine is upstream, the buffers are for housing the articles coming from it when the downstream machine is momentarily out of commission.
Thereafter, once regular functioning of the downstream machine has been restored, the accumulation of articles in the buffer can be disposed of in various ways, according to possibilities as follow:                if the downstream machine is able to go faster than the upstream machine, the accumulation can be gradually dispensed of;        if, on the other hand, the downstream machine is not able to go faster than the upstream machine, either the speed of the upstream machine is temporarily reduced or, alternatively, the build-up is manually removed from the buffer, kept off-line and possibly re-introduced at the end of the batch.        
In other cases, in which the more delicate machine is downstream, the buffers are preliminarily filled, anticipating the start-up of the upstream machine with respect to the downstream machine; in this way the accumulation of articles in the buffer guarantees a reserve supply for the downstream machine if the upstream machine is faulty.
At the end of the batch, the buffer is emptied.
For particularly fragile articles (e.g. glass vials, glass syringes, etc.) the means for performing the transfer, as well as the buffer devices, must be conformed such as not to lead to, or at most to reduce to an insignificant minimum, impacts between the articles in order to prevent damage; these technical-functional aspects are obtainable only at considerable cost.
The operating modalities of the system, which include the emptying of the articles in the buffer at the end of work, can become incompatible with the requirements of certain products which, for example, are damaged or altered if kept for too long at higher-than-predetermined temperatures: in fact the temperature is not controlled in the buffer and depends on the environment the machines are located in.